Drafting mechanism for roving frames



July 6, 1943, B. c. SHAW DRAF TING MECHANISM FOR ROVING FRAMES FiledApiil 24, 1941 2 Sheets-Sheet l QIMHUHHHHWHHr' July 6, 1943. B. c. SHAW1 2,323,832

' DRAFTING MECHANISM FOR ROVING FRAMES Filed April 24, 1941 2Sheets-Sheet 2 Patented July ,6, 1943 DRAFTING MECHANISM F OR ROVINGFRAMES Benjamin C. Shaw. Saco. Maine, assignor to Saco-Loweli Shops,Boston, Mass., a corporation of Maine Application April 24, 1941, SerialNo. 390,089

(Cl. l9130) 13 Claims.

This invention relates to roving frames. As is well understood by thoseskilled in the art of manufacturing cotton textiles, the sliverdelivered by a card usually is subsequently subjected to one or moredrawing operations and then goes to a roving frame which prepares it fordelivery to a spinning frame. The roving frame includes a drawingmechanism which drafts or attenuates the strands of sliver, both for thepurpose of disposing the fibers in a more nearly parallel relationshipto each other and also reducing the cross-sectional dimensions of thestrands to those suitable for the next succeeding operation.

A serious dimculty in drafting cotton and similar slivers is to maintainthat control of the fibers necessary to produce a roving having thedesired degree of uniformity, In other words, as the fibers are drawnout there is a strong. tendency for them to bunch and thus to produce aproduct that varies greatly in cross-sectional dimensions and in thenumber of fibers present in successive portions of the-strand. In fact,close examination of commercial rovings shows a sur prising degree ofirregularity or non-uniformity amounting, at times. to as much as 200%or 300% in the same roving. It is obvious that when such a roving istwisted into a yarn the inch for inch strength of that yam will varycorrespondingly, or perhaps to an even higher degree, so that thismatter of uniformity in the roving is extremely important in producing ayarn ofgood quality.

The present invention deals particularly with these conditions, and itaims to devise a drafting mechanism for roving frames which will beexceptionally simple in construction, reliable in operation, easyto'take care of, and will be so organized as to maintain anexceptionally high degree of control of the fibers as the strands aredrawn out and attenuated.

The nature of the invention will bereadily understood from the followingdescription when read in connection with the accompanying drawings, andthe novel features will be particularly pointed out in the appendedclaims.

In thedrawings,

Figure 1 is a vertical, sectional view, partly in elevation, of adrawing mechanism constructed in accordance with this invention;

Fig. 2 is a similar view but the plane of section being taken throughthe necks of the drawing rolls; and

- Fig. 3 is a sectional view on the lin 3-3, Fig. 1, with the rolls"shown partly in elevation and partly in section. v

The construction shown in the drawings comprises a pair of top andbottom front rolls 2 and 3, respectively, a second pair of top andbottom rolls 4 and 5, and a pair of rear rolls t and I. These rolls arearranged in series so that a strand rolls.

of roving fed through them is drawn between the rear and middle rollsand again between the latter rolls and the front rolls. Between thefirst and second bottom rolls is an intermediate bottom roll 8,preferably smaller in. diameter than the other bottom rolls, and it ismounted closely adjacent to the lower surface of the second top roll 4.

All of the bottom rolls are supported in bearing blocks mounted in aroll'stand ill for relative adjustment to vary the roll spacing as maybe required for different staples, and these rolls are driven fromgearing usually mounted at one end of the frame. Such gearing hasprovision for adjustment to change the draft exerted on the sliver as ittravels through the rolls. The top rolls are held in spaced relationshipto each other by a suitable cap bar it equipped with adjustable guidingblocks for the front and rear rolls, as is customary in mechanisms ofthis character. Also, a weighting mechanism is provided to maintain theroll 4 pressed continuously against its cooperating lower roll 5 so thata firm-bite is provided between them enabling these rolls to draw thefibers fromthe rear rolls 5 and l, and also to exert the necessaryholding action on the sliver while the front rolls 2 and 3 perform theirdrawing function.- In addition, this weighting mechanism acts on thefront and rear rolls to maintain firm bites on the sliver as it is fedby them.

Since the slivers fed to a roving frame are almost entirely devoid oftwist, a substantial draft in the neighborhood of, say, 2% or 3, iscustomarily applied between the rear and middle rolls, and a higherdraft such, for example, as 5 or 6, may be used between the middle andfront The chief difficulty in the control of the fibers, therefore, isin the front draft,

The present invention solves this difilculty by so mounting theintermediate lower roll 8 and the second top roll a that they are alwaysspaced apart by a small distance, say five or ten thousandths of aninch. For this purpose two spacing collars l3--fi3; best shown in Fig.3, are mounted for rotation on the gudgeons projecting from the oppositeends of the top roll t and the peripheral edges of these collars rest onthe reduced portions of the bottom intermediate roll .8. These parts aremade of such dimensions that the desired minimum spacing will bemaintained between the bosses t-& of the upper roll and those of thelower roll.

This arrangement has been found to produce exceptionally uniform roving,and experiments have shown that this is due directly to the spacedrelationship of the intermediate lower roll 8 to the top roll 4. Thereasons for this favorable result are somewhat obscure. The bestexplanation which I am able to give at this time is that the rolls I and8 cooperate to exert a limited com- I such travel and for a distanceafter leaving pressing action on the fibers in the region between thefront andmiddle firm bites where the maximum movement of the fibers overeach other presumably is taking place. As the front rolls draw thefibers through the restricted space between the rolls 4 and 8, anytransversely disposed ends between this space and the middle firm biteare yieldingly restrained so that the I drawing action tends tostraighten them out. The higher surface speed of the bottom roll 8, ascompared to that of its cooperating roll 4, also contributes to thisfiber straightening action.

The shorter fibers which momentarily are not gripped at either bite canonly be drawn forward by their contact with longer fibers. There is astrong tendency for the free ends of any of the fibers to spring outaway from the main body of the sliver, if they are free to do so,probably due to the presence of static charges created by the movementsof the slivers over each other. The pressure applied to the slivers bythe rolls 4 and 8 controls this action and, in addition, it presses theshorter fibers more firmly into contact with the longer ones so that thelatter can carry them along.

In addition, it should be observed that as any.

of the fibers leave the middle bite, the portion of the sliver of whichthey form a part is held for a considerable distance in contact with theperipheral surface of the top the latter roll, this part of the sliveris held in contact with the peripheral surface of the lower roll 8. Theangle of this contact with the upper roll should be between 45 and 60and with the lower roll should be in the neighborhood of as in thearrangement shown, so that so long as the slivers are in contact withthe surface of either of these two rolls and are being drawn through thereversely curved path provided by these rolls, they are still under arestraining pressure which tends to hold the shorter fibers in contactwith the longer ones and thus to assist in making the short fiberstravel with the longer ones. This action thus contributes to theproduction of a more uniform sliver.

A further factor which is believed to contribute to thefavorable-results produced by this mechanism is that the surfacesbetween which the restriction just referred to is provided, arecontinuously moving forward in the direction of travel of the sliver.They do not move as fast as do the fibers, due to the drafting action ofthe front rolls, but they do seem to modify beneficially the retardingaction of the restriction through which the fibers are pulled by thefront rolls. That. this factor is helpful is indicated by the fact thatthe best results have been produced by sand blasting the fiber engagingbosses of the lower roll 8 instead of making these surfaces smooth orpolished.

Whatever may be the reasons for the improved results obtained, theimportant fact is that this mechanism has been found in practice toproduce exceptionally uniform rovings.

Preferably the intermediate lower roll 8 is driven at a slightly higherperipheral speed than the roll 5 in order to exert a rubbing and pullingaction on the forward ends of the fibers tending to straighten andparallelize them as they come in contact with it, to prevent thecreation of any slack in the sliver between these two rolls andtoincrease the pressure of the sliver against the lower surface of theupper roll a. Such a difference in speed, while maintaining the desiredroll 4, and during relative spacing of the rolls with reference to eachother, is facilitated by the fact that the spacing collars can revolvewith reference to both the of the collars produced by their contact withthe lower roll 8 will not adversely affect the rotation of the upperroll. The clearance between the rolls 4 and 8 can .be increased from thefigure of five thousandths of an inch above given to in the neighborhoodof thirty-five thousandths of an inch while still producing goodresults. Usually it is preferable to maintain this clearance somewherebetween five and twenty or twentyfive thousandths. In general, it isdesirable to make this clearance as small as is consistent with goodoperating conditions. In this connection, however, it should be notedthat the density of the fiber inthe restricted space between the rolls 4and 8 can be adjusted by suitably varying the relationship between thetwo drafts. That is, if the density of the fiber is too high the reardraft can be increased slightly to bring the density'down to the desiredvalue, and the overall draft can still be maintained unchanged bydecreasing the front draft to compensate for the increase in the reardraft. Thus a very considerable operating flexibility is obtainable witha given spacing between the rolls 4 and 8.

Since the top roll 4 is mounted in the crotch of the lower roils5 and 8,or more accurately stated, is positioned transversely of the frame bythe engagement of its bosses with the lower roll 5 and the contact ofthe spacing collars with the intermediate lower roll 8, no engagementwith the cap bars is required so far as the matter of holding itproperly spaced from the front and rear rolls is concerned. However, thecap bars are provided with blocks I4-l4, Fig. 3, to limit any tendencyof the top roll to move axially of itself. The spacing of the middleassembly of rolls, including those designated at 4, 5 and 8, may bechanged by adjusting the bearing block l5, Fig. 1, backward or forwardwith the slide IS on the roll stand [0. Also, the lower rear roll I maybe adjusted toward and from roll 5 by moving its bearing block l8 on theslide l6. Bolts are provided to lock these elements in their adjustedpositions.

As in any drafting system, the spacing of the three sets of rolls willdepend largely upon the average length of staple undergoing operation,the distance between the bite of the middle roll andthe rear rolls, aswell as that between the middle and front rolls, than such averagelength. It should be observed, however, that when the parts areadjusted, as

' shown in Fig. l, the distance from the bite of the in accordance withfront roll to the point at which the sliver leaves the bottom roll 8. isless than half the staple length, which is a good operating condition.Also, that the machine has provision for a wide range of adjustment ofthe roll spacings so that it is well adapted for operation on the longerstaples, such as combed cotton and mixtures of cotton or wool withrayon.

The bottom rolls 3, 5 and 1 preferably are fluted the usual practice andthe top rolls are covered, as is common in mechanisms of this type, withsome cushioning material, such as leather, synthetic rubber, orsynthetic plastics having the desired cushioning and oil-resistingproperties.

The weighting mechanism showncomprises a hanger 20 hooked over the neckof the front roll 2 and a saddle 2| with its front end hooked over rolls4 and 5 so that the speed of rotation the middle being somewhat greaterasaaasa the neck of the top middle roll 4, and its rearward end restingon the neck of the rear roll 8. A stirrup 22 has a hooked end resting inthe V-shaped bend in the saddle 2| and the lower ends of this stirrupand of the hook 213 are pivoted to opposite ends of a floating lever 23connected by a link 24 with aweighting lever 25 mounted in a manner wellknown in this art. It will be evi= dent from an inspection of Fig. 2that the angle of pull exerted by this mechanism on the second top roll4 is directed downwardly and rearwardly at such an angle that it passesthrough the lower roll 5 and thus maintains the firm bite of these rollsreferred to above.

While I have herein shown and described a preferred embodiment of myinvention, it will be evident that the essential features of theinvention may be embodied in other forms.

Having thus described my invention, what I desire to claim as new is:

1. In a drafting mechanism for roving frames, the combination of a pairof top and bottom front rolls, a second pair of top and bottom rollsbehind the front pair and driven at a slower speed than the first pairfor grippinga sliver and feed-" ing it toward the front rolls, weightingmeans for loading the second top roll to produce a firm bite between therolls of said second pair, an intermediate bottom roll between saidfront and second bottom rolls cooperating with said second top roll toengage and compress the sliver without gripping it firmly as it is drawnforward between them by the front rolls, and means for maintaining saidsecond top roll and said intermediate bottom roll spaced apart by apredeter mined minimum distance, whereby a positive draft is producedbetween said first and second pairs of rolls and a slip control of thefibers is provided between said second top roll and said intermediatebottom roll.

2. A drafting mechanism according to preceding claim 1, in which saidspacing means is supported for rotation relatively to both said secondtop roll and said intermediate bottom roll.

3. A drafting mechanism according to preceding claim 1, in which saidspacing means includes spacing collars mounted to roll relatively toboth said second top roll and said intermediate bottom roll andsupporting said second top roll.

4. A drafting mechanism according to preceding claim 1, in which. saidspacing means includes collars rotatably mounted on the gudgeons of saidsecond top roll and resting on said intermediate bottom roll.

5. A drafting m'echanismaccording to preceding claim 1, in which saidbottom rolls run at progressively increased speeds with the front rollrunning at the highest speed. I

6. A draftingmechanism according to preceding claim 1, in which saidsecond top roll is located in. the crotch between said second andintermediate bottomrolls and the latter are so spaced apart that thesliver is in contact with the top roll for an angle of at least 45contact with the bottom roll for in the hood of 7. A drafting mechanismaccording to precedneighboring claim 1, in combination with weightingmeans for said top rolls and the weight is so applied to said second topr011 that'the line of pull exerted on it passes through said secondbottom roll.

8. A drafting mechanism according to preced-' ing .claim 1, in whichthespace so maintained between said second top roll and saidintermediate bottom roll is in the neighborhood of five thousandths ofan inch.

9. A drafting mechanism according to preceding claim 1, in which thespace so maintained between said second top roll and said intermediatebottom roll is between five and thirtyfive thousandths of an inch.

10. In adrafting mechanism for roving frames, the combination of a pairof top and bottom front rolls, a pair of upper and lower back rolls andan intermediate set of rolls comprising two bottom rolls and a top rollpositioned in the crotch between said intermediatebottom rolls, all ofsaid rolls cooperating to feed and draw a strand of andisin' the toprolls to maintain a firm sliver, means maintaining the foremost of saidintermediate bottom rolls and said intermediate top roll separated by anarrow space of predetermined minimum thickness such that the sliver is'compressed between them but is not gripped firmly by them, andweighting means acting on bite between each of said front and back toprolls and its respective lower roll and also between said intermediatetop roll and the rearmost of said intermediate bottom rolls.

11. In a drafting mechanism for roving frames, the combination of pairsof top and bottom front and rear rolls, a second pair of top and bottomrolls between said front and rear rolls, all of said rolls beingarranged in a series to grip and feed a sliver and to subject it to twodrafting operations, weighting means acting on said top rolls to producea firm bite between each of them and their respective bottom rolls, anintermediate bottom roll between said front and second bottom rolls,driven at a higher speed than said second bottom roll and cooperatingwith said second top roll to engage and compress the sliver as it movesforward to the front rolls, means for maintaining said second top rollspaced from said intermediate bottom roll by a predetermined minimumdistance, and means supporting said rolls in cooperative relationship toeach other with the second top roll located in the crotch between saidsecond and intermediate bottom rolls and thereby causing the sliver toremain in contact with the peripheral surface of the second top roll foran angular distance of at least 30.

12. A drafting mechanism according to preceding claim 1, in which saidintermediate bottom roll is driven at a higher surface speed than itscooperating second top roll and said spacing means between these tworolls includes collars mounted in a fixed radial relationship to saidtop roll for rotation around the axis of the latter roll while bearingon the peripheral surface of said intermediate bottom roll.

13. In a drafting mechanism according to preceding claim 10, aconstruction in which the foremost of said intermediate bottom rolls isdriven at a higher surface speed than its cooperating top roll and thesetwo rolls are spaced apart by BENJAMIN c. snaw.

